CVE-2026-64331: In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: fix NULL deref in vep_dequeue() vep_alloc_request() wasn't initiali...

Description

In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: fix NULL deref in vep_dequeue() vep_alloc_request() wasn't initializing vrequest->udc, so cancellations on the FunctionFS AIO path were arriving in vep_dequeue without a valid UDC reference. Since vrequest->udc is never actually properly used anywhere, we opt to remove it, and update vep_dequeue to obtain a reference to the udc with ep_to_vudc(), consistent with the other vep_ ops. AFAICT this bug has existed for ~10 years. Seems that nobody has really stressed the FunctionFS AIO path on usbip's vudc. I tested this fix in a QEMU aarch64 guest driving FunctionFS endpoints via AIO. Before the fix, running `usbip attach` from the host would cause the guest to oops with the following backtrace: Call trace: vep_dequeue+0x1c/0xe4 (P) usb_ep_dequeue+0x14/0x20 ffs_aio_cancel+0x24/0x34 __arm64_sys_io_cancel+0xb0/0x124 do_el0_svc+0x68/0x100 el0_svc+0x18/0x5c el0t_64_sync_handler+0x98/0xdc el0t_64_sync+0x154/0x158

Metrics

EPSS Probability

0.18%

7.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= b6a0ca11186759ad7045d68a5447b1e89f658384, < 9858c91d9ee6a13c45311569039413729fc9b757; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < 1226293ec9bed3d4cc5b05eeeb811d315ca51652; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < 3750f75f29f99c0223601e2ee73ad084adec47bd; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < 0025276175fbbe0dcbf3f84d090b0adee769e9d9; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < 347b59e9f96719d89b6ef555d02a18ada1a5846f; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < 0443e4416aa1ee97748d1ed904eaf3352c60045e; >= b6a0ca11186759ad7045d68a5447b1e89f658384, < c5371e0b91b24159a3ebaa61e70b0980bcf03c0a
Linux	Linux	4.7

References

Timeline

Published: Jul 25, 2026
Last Modified: Aug 11, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-64331?

In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: fix NULL deref in vep_dequeue() vep_alloc_request() wasn't initializing vrequest->udc, so cancellations on the FunctionFS AIO path were arriving in vep_dequeue without a valid UDC reference. Since vrequest->udc is never actually properly used anywhere, we opt to remove it, and update vep_dequeue to obtain a reference to the udc with ep_to_vudc(), consistent with the other vep_ ops. AFAICT this bug has existed for ~10 years. Seems that nobody has really stressed the FunctionFS AIO path on usbip's vudc. I tested this fix in a QEMU aarch64 guest driving FunctionFS endpoints via AIO. Before the fix, running `usbip attach` from the host would cause the guest to oops with the following backtrace: Call trace: vep_dequeue+0x1c/0xe4 (P) usb_ep_dequeue+0x14/0x20 ffs_aio_cancel+0x24/0x34 __arm64_sys_io_cancel+0xb0/0x124 do_el0_svc+0x68/0x100 el0_svc+0x18/0x5c el0t_64_sync_handler+0x98/0xdc el0t_64_sync+0x154/0x158

How severe is CVE-2026-64331?

Severity scoring for CVE-2026-64331 is pending analysis. The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.

How do I fix CVE-2026-64331?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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